The system of pre-fabricated slabs is one of the most widely used in civil construction of slabs to be used in floors and roofs. The pre-fabricated slabs include a set of ribs (slabs with reinforced concrete rods which gives structure and strength to the slab), and the blocks (hollow units that are placed as a supporting base for the fresh concrete which is tamped in the top section) that, different from the ribs have no structural function and it is just a dead load (weight due to the mass itself placed on the structure). In all, ribs and blocks a layer of concrete is placed and tamped. The work required to place the blocks between the small beams is a time consuming task, hazardous and arduous. The blocks have no structural function, but become a support for the concrete (while it is fresh) poured on the top of the slab, and the lower face acts to support the finishing mortar for the stucco and ceiling finishing work.
Recently, the use of the expanded foam blocks have been used to replace concrete or ceramic blocks. This technique diminished work accidents due to the fall of blocks as well as the worthless load put on the slabs due to the mass weight of the blocks. However, since the expanded foam blocks compact and are fragile they call for additional handling care as regard to bracing, the motion of workmen or the top of the structure at the time of pouring, excavation or cut to suit work to make way for ducts and conduits along the blocks. Furthermore, the expanded foam blocks impair the placing of switches and finishing work using gypsum plates finishing work due to low strength and the absence of hang spots to support the plates, thus requiring additional work to overcome these shortcomings.